Thanks for your reply! As I said, I thought the gap between the crank surface and the end of the spindle taper looked correct, and I'm definitely aware that it should not be flush. I mostly just want to make sure that everything looks okay otherwise and that I can do as you say - put a new bolt on and monitor for cracks. This is a pretty common configuration as it's the stock 70s PX-10 setup, but I can't seem to find any pictures showing this detail.